Reproduction of sound records



""'4 3619i 2 T1937 K. SCHWARZ $93,436

REPRODUCTION OF SOUND RECORDS Filed July 2, 1955 'Patented Sept. El, i193? Karl Schwarz, Berlin,

Klangiilm G. m. b. Xi., poration of Germany Germany, assigner to Berlin, Germany, a. cor= applicati@ July 2, 1935, seriai- No. 29,439

In Germany Sept ernbcr 26, 1934 4 Claims. (CL 179-1003) This invention relates to the reproduction of sound records of the type whercon a negative and positive half-cyclo of the sound wave are recorded in the form of sound tracks spaced from one an- .i other, and has for its principal object the provision of an' improved arrangement for transmitting the sound track modulated light to the photo-electric or light sensitive elements by which the vmodulated light is converted into cfrrespondlu ing audiofrequency currents.

There has been provided in the past an arrangement which serves the purpose of diascopically scanning a band-shaped sound track or record, preferably a iilm strip photo-electrically,

and in which between two drum halves supportinf,r a sound track there is provided a straight glass rod designedv to deflect the light transmitted through the sound track to a photo-'electric cell.

The present invention is concerned with an improved arrangement of such means to reproduce sound records in which the positive and the negative half-cycles are recorded in the form of separate tracks.

The embodiments of the invention described in Ywhat follows are schematically illustrated in the drawing. What is common to all embodiments is the fact that for each of the two separate sound tracks a rod of quartz, glass or the like is provided. v

The invention will be better understood from ,l the following description when considered in conncction with the accompanying drawing, and its scope will be pointed out in the appended claims.

Referring to the drawing,

Figures 1 and laare diagrammatic showings of side and plan views of a sound reproducer constructed in accordance with the invention, and

lFigsl 2, 3 and 4 illustrate different modifica tions of the light transmitting means interposed between the sound record and the photo-electric cell or cells.

Referring t'o Fig. l, l0 denotes a sound lm strip which is moved by means of a sprocket (not shown) over a drum consisting of two parts li and l2 and xedly mounted upon a common spindle i3. This drum which is set in rotation by the said lm strip may be rigidly coupled with a iiywheel mass or other suitable speed stabilizer.- The divided or bipartite sound track 23, 2li which is here shown to be of the 'variable density type although it could just as well consist of the variable area kind, is illuminated in a manner customary in reproducer or projector equipment. .i Between the two halves of the drum il, I2 are two straight glass rodlets 25, 25 of rectangular v this action is cross-sectional shape, which by the use of a rev iective interposed layer 2 are cemented together.

ly reflected on the inner face ofthe glass surfaces 10 bounded by air so that the two rod's. insofar as concerned, will reforward the light without incidental losses, in fact, only a slight loss of light is caused because of absorption in the rods. The reflecting intermediary layer 21 be- 15 tween the two rods prevents also paage of light from one rod to the other. Beyond the peint where the conical glass parts 30, 3l begin, reiiection occurs in the rod only on the reflecting intermediary layer 21, while no reectionoccurs any 2U more on che rod walls. Hence, looking in the surface of the plane in Fig. l, the light rays emerge from the cone-shaped parts 3l, 32 in such a way that they will strike the two photo-electric cells which are coordinated to the two sound tracks ill, 25 l5, while light rays emerging from one glass rod will not partly impinge also upon the other photocell, and vice versa, though this would be the case if the two glass rods were not provided with the Vtwo wedgeor cone-shaped enlargements at 30 th;r ends. Y

Fig. 2 shows another embodiment in which the two glass rods 25, 2S are placed a small distance d apart in such a way that they will be separated by a small, but nite, layer of air. In this form 35 of construction the reflective intermediary layer 2l in Fig. 1 is dispensable.

Fig. 3 shows another embodiment n which a simplication has been adopted in that the cone- -shaped terminal pieces 3B, 3l which have been 40 described by reference to Fig. 1 are dispensed with. The rods 25, 26 are disposed in such a way that their axes diverge slightly in the direction of the photo-electric cells. The glass rods may terminate in planar surfaces towards the photocells. In this arrangement the light rays emerge from the two glass rods in the form of a pencil presenting comparatively large divergence. By virtue of the great distance separating the two glass rods, however, no illumination of the photoceii 35 (which may be used instead of the two distinctvcells shown in Figs. 1 and 2 where they could also be united into one cell) will be produced in the cathode coordinatedcyto the respective other rod.. a

Fig. i shows a scheme in which, contradistinct to the arrangements in Figs. l-3, the tiro glass rods are disposed upon diilerent sides or the sound piek-up drum spindle i3. In this arrangenient, according to desires, the two rods 25 and 2G along the surface a, D, c, as shown in Fig. l may ne cemented together by the aid of an interposed reflecting layer, or else, as in Fig. 2, be spaced aparta certain finite distance.

I claim:

l. In an apparatus for reproducingr a sound record whereon the positive and negative hali Cycle tracks are spaced from one another, the Combination of means for supporting said record, light sensitive means including a plurality of eaihodes, and a plurality of transparent rods interposed between said record and said light .sensitive means each arranged to transmit light between a different one of said tracks and said light sensiire means.

2. In an apparatus for reproducing o. sound record u'liereon the positive and negative lialcycle tracks are spaced from one another, the eomliinfi'ion o means for supporting said record, light sensitive means including a. plurality of eatnodes, and a plurality of transparent rods each conically-sliaped at one of its ends inter posed between said record and said light sensirive means each arranged to transmit light lietween a different one of said tracks and said light sensitive means.

3, n an apparatus for reproducing e. sound record Whereon the positive and negative halfcyele tracks are spaced from one another, the combination of means for supporting said record, light sensitive means including a plurality of eaihodes, a plurality of transparent rods nterposed between said record and said light sensitive means each arranged to transmit light between o, dfierent one of said tracks and said light sensitive means, and a. layer of reflective material interposed between said rods.

4. In an apparatus for reproducing a. sound. record 'whereon the positive and negative half'I cycle tracks are spaced from one another, the combination of means for supporting said record, light sensitive means including a plurality of cathodes, and a plurality of angularly displaced transparent rods interposed between said record and said light sensitive means each arranged, t0 transmit iight between a different one of said tracks and said light sensitive means.

KARL S CHVJARz. 

